OLED array substrate, OLED display panel, pixel circuit, driving method and method for fingerprint recognition using OLED display panel

ABSTRACT

The embodiments of the present disclosure disclose an OLED array substrate. The OLED array substrate comprises: a plurality of scan lines; a plurality of data lines; a plurality of OLED pixel units, each OLED pixel unit is connected to a corresponding data line and a corresponding scan line and being connected to a corresponding reset terminal; and a plurality of light detection units, each light detection unit is connected between the reset terminal of one OLED pixel unit and the corresponding data line, is configured to detect a light emitted by a detection light resource to generate a light detection signal, and output the light detection signal via the corresponding data line under a control of a reset signal from the reset terminal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of China Patent Application No.201710287382.4, filed on Apr. 27, 2017, the entire content of which isincorporated herein by reference as part of this application.

TECHNICAL FIELD

Embodiments of the present disclosure relate to a field of displaytechnology, and in particular, to an organic light emitting diode (OLED)array substrate, an OLED display panel, a pixel circuit, a drivingmethod and a method for fingerprint recognition using the OLED displaypanel.

BACKGROUND

With the development of display technology, many display devices such asmobile phones, tablet computers or the like have fingerprint recognitionfunctions. Current fingerprint recognition sensors can comprise threetypes. The first type is an optical sensor which has a larger size. Thesecond type is a capacitive sensor, the dots per inch (dpi) required bywhich is higher. The third type is an ultrasonic sensor.

SUMMARY OF THE INVENTION

The embodiments of the present disclosure provide an OLED arraysubstrate, an OLED display panel, a pixel circuit, a driving method anda method for fingerprint recognition using the OLED display panel, whichcan perform fingerprint recognition while displaying without affectingthe accuracy of fingerprint recognition.

According to a first aspect of the embodiments of the presentdisclosure, there is provided an OLED array substrate. The OLED arraysubstrate comprises a plurality of scan lines, a plurality of datalines, and a plurality of OLED pixel units. Each of the OLED pixel unitsmay be connected to a corresponding data line and a corresponding scanline and being connected to a corresponding reset terminal. The OLEDarray substrate further comprises a plurality of light detection units.Each of the light detection units may be connected between the resetterminal of one of the OLED pixel units and the corresponding data lineand be configured to detect a light emitted by a detection lightresource to generate a light detection signal. In addition, each of thelight detection units can also output the light detection signal via thecorresponding data line under a control of a reset signal from the resetterminal.

In an embodiment of the present disclosure, each of the OLED pixel unitscomprises a plurality of sub-pixel units. One of the light detectionunits may be connected between the reset terminal of at least one of thesub-pixel units and the corresponding data line.

In an embodiment of the present disclosure, the light detection unitcomprises a first transistor and a photodetector. A first electrode ofthe first transistor is coupled to the corresponding data line. A secondelectrode of the first transistor is coupled to the photodetector. Acontrol electrode of the first transistor is coupled to the resetterminal.

In an embodiment of the present disclosure, a orthographic projection ofthe light detection unit on a substrate of the OLED array substrate doesnot overlap with a orthographic projection of an organic light emittinglayer of the OLED pixel unit on the substrate.

In an embodiment of the present disclosure, the photodetector maycomprise a photodiode.

In an embodiment of the present disclosure, the detection light resourceis the OLED pixel unit.

In an embodiment of the present disclosure, the light emitted by thedetection light resource is monochromatic light.

According to a second aspect of the embodiments of the presentdisclosure, there is provided an OLED display panel comprising theabove-described OLED array substrate. The OLED display panel furthercomprises a transparent substrate disposed opposite to the OLED arraysubstrate and a fingerprint recognition unit which is connected to theplurality of data lines and is configured to recognize a fingerprintpattern based on the light detection signals from the plurality of datalines.

In an embodiment of the present disclosure, the light emitted by thedetection light resource is a light reflected by the transparentsubstrate.

According to a third aspect of the embodiments of the presentdisclosure, there is provided a pixel circuit for the above-describedOLED display panel. The pixel circuit comprises a light emitting drivecircuit being configured to control an OLED pixel unit to emit light;and a light detection unit being configured to detect a light emitted bya detection light resource to generate a light detection signal.

In an embodiment of the present disclosure, the light detection unitcomprises a first transistor and a photodetector, a first electrode ofthe first transistor is coupled to a corresponding data line, a secondelectrode of the first transistor is coupled to the photodetector, and acontrol electrode of the first transistor is coupled to a resetterminal.

In an embodiment of the present disclosure, the light emitting drivecircuit comprises a capacitor, an initialization transistor, a secondtransistor, a third transistor, a fourth transistor, a fifth transistor,a sixth transistor, a driving transistor, and an OLED light emittingdevice. A control electrode of the initialization transistor is coupledto the reset terminal, a first electrode of the initializationtransistor is coupled to a first terminal of the capacitor, and a secondelectrode of the initialization transistor is used for receiving aninitial supply voltage. A control electrode of the second transistor iscoupled to a corresponding scan line, a first electrode of the secondtransistor is coupled to a second electrode of the driving transistor,and a second electrode of the second transistor is coupled to the firstterminal of the capacitor. A control electrode of the third transistoris coupled to the corresponding scan line, a first electrode of thethird transistor is coupled to the corresponding data line, and a secondelectrode of the third transistor is coupled to a first electrode of thedriving transistor. A control electrode of the fourth transistor iscoupled to a light emission control signal line, a first electrode ofthe fourth transistor is coupled to the first electrode of the drivingtransistor, and a second electrode of the fourth transistor is coupledto a second terminal of the capacitor. A control electrode of the fifthtransistor is coupled to the light emission control signal line, a firstelectrode of the fifth transistor is coupled to the OLED light emittingdevice, and a second electrode of the fifth transistor is coupled to thesecond electrode of the driving transistor. A control electrode of thesixth transistor is coupled to the reset terminal, a first electrode ofthe sixth transistor is used for receiving the initial supply voltage,and a second electrode of the sixth transistor is coupled to the OLEDlight emitting device. A control electrode of the driving transistor iscoupled to the first terminal of the capacitor, the first electrode ofthe driving transistor is coupled to the first electrode of the fourthtransistor, and the second electrode of the driving transistor iscoupled to the second electrode of the fifth transistor.

According to a fourth aspect of the embodiments of the presentdisclosure, there is provided a driving method of the above-describedpixel circuit. The pixel circuit comprises during a first time period,resetting an OLED pixel unit, during a second time period, storing adata voltage for displaying, and during a third time period, driving theOLED pixel unit to emit light.

According to a fifth aspect of the embodiments of the presentdisclosure, there is provided a method for fingerprint recognition usingthe above-described OLED display panel. In this method, it is detectedthat a user's finger touching the OLED display panel. An OLED pixel unitof the OLED display panel is controlled to emit a light for fingerprintrecognition. Then, in a reset stage of the OLED pixel unit of the OLEDdisplay panel, a light detection signal is obtained, wherein the lightdetection signal is generated by detecting the light for fingerprintrecognition reflected by the transparent substrate of the OLED displaypanel. Finally, based on the light detection signal, a fingerprintpattern of the user's finger can be recognized.

In an embodiment of the present disclosure, a region for fingerprintrecognition may also be provided in a display region of the OLED displaypanel. In addition, the detecting that a user's finger touching the OLEDdisplay panel may comprise detecting that a user's finger touching theregion for fingerprint recognition for a predetermined time.

In an embodiment of the present disclosure, the light for fingerprintrecognition is monochromatic light.

According to a sixth aspect of the embodiments of the presentdisclosure, there is provided an electronic device which comprises theabove-described OLED display panel.

Further aspects and areas of applicability will become apparent from thedescription provided herein. It should be understood that variousaspects of this application may be implemented individually or incombination with one or more other aspects. It should also be understoodthat the description and specific examples herein are intended forpurposes of illustration only and are not intended to limit the scope ofthe present application.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present application.

FIG. 1 is a schematic view of a cross section of an OLED display panelaccording to an embodiment of the present disclosure;

FIG. 2 is a schematic plan view of one example of an OLED display panelaccording to an embodiment of the present disclosure;

FIG. 3 is a schematic structural diagram of a light detection unitaccording to an embodiment of the present disclosure;

FIG. 4 is an exemplary pixel circuit schematic diagram of an OLEDdisplay panel according to an embodiment of the present disclosure;

FIG. 5 is an operation timing chart of a pixel circuit of an OLEDdisplay panel according to an embodiment of the present disclosure;

FIG. 6 is a flowchart of a method for fingerprint recognition using anOLED display panel according to an embodiment of the present disclosure;

FIG. 7 is a schematic structural diagram of an electronic deviceaccording to an embodiment of the present disclosure.

Corresponding reference numerals indicate corresponding parts orfeatures throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

As used herein and in the appended claims, the singular form of a wordincludes the plural, and vice versa, unless the context clearly dictatesotherwise. Thus, the references “a”, “an”, and “the” are generallyinclusive of the plurals of the respective terms. Similarly, the words“comprise”, “comprises”, and “comprising” are to be interpretedinclusively rather than exclusively. Likewise, the terms “include”,“including” and “or” should all be construed to be inclusive, unlesssuch a construction is clearly prohibited from the context. Where usedherein the term “examples,” particularly when followed by a listing ofterms is merely exemplary and illustrative, and should not be deemed tobe exclusive or comprehensive.

Further to be noted, when the elements and the embodiments thereof ofthe present application are introduced, the articles “a/an”, “one”,“the” and “said” are intended to represent the existence of one or moreelements. Unless otherwise specified, “a plurality of” means two ormore. The expressions “comprise”, “include”, “contain” and “have” areintended as inclusive and mean that there may be other elements besidesthose listed. The terms such as “first” and “second” are used hereinonly for purposes of description and are not intended to indicate orimply relative importance and the order of formation.

The flow diagrams depicted herein are just one example. There may bemany variations to this diagram or the steps (or operations) describedtherein without departing from the spirit of the invention. Forinstance, the steps may be performed in a differing order or steps maybe added, deleted or modified. All of these variations are considered apart of the claimed invention.

Example embodiments will now be described more fully with reference tothe accompanying drawings.

In an embodiment of the present disclosure, an OLED display panel isprovided. The OLED display panel can perform fingerprint recognitionwhile displaying without affecting the accuracy of fingerprintrecognition.

FIG. 1 is a schematic view of a cross section of an OLED display panel10 according to an embodiment of the present disclosure. As shown inFIG. 1, the OLED display panel 10 comprises a transparent substrate 1and an OLED array substrate 2 disposed opposite to the transparentsubstrate 1. The OLED array substrate 2 comprises: a substrate 21; andan OLED pixel unit 221 and a light detection unit 222 on the substrate21. Each light detection unit 222 may be connected between a resetterminal of one OLED pixel unit 221 and a data line. The OLED displaypanel 10 further comprises a fingerprint recognition unit (not shown).

In the embodiments of the present disclosure, each light detection unit222 is configured to detect a light emitted by a detection lightresource to generate a light detection signal and output the lightdetection signal via the data line under a control of a reset signalfrom the reset terminal.

In an exemplary embodiment, the detection light resource is the OLEDpixel unit.

In an exemplary embodiment, the light emitted by the detection lightresource is monochromatic light.

In an exemplary embodiment, the light emitted by the detection lightresource is a light reflected by the transparent substrate.

In an exemplary embodiment, the transparent substrate 1 may be asubstrate which can transmit light. As an example, the transparentsubstrate 1 is a glass substrate. As another example, the transparentsubstrate 1 may be made of a transparent flexible material.

In an exemplary embodiment, the OLED pixel unit 221 may comprise aplurality of sub-pixel units. For example, an OLED pixel unit may beimplemented to comprise three sub-pixel units of red, green and bluesub-pixel unit. As another example, an OLED pixel unit may also beimplemented to comprise other numbers of sub-pixel units. In this case,sub-pixel units in different OLED pixel units can be shared by drivecontrol.

In the embodiments of the present disclosure, one light detection unit222 may be correspondingly provided for each OLED pixel unit 221. Inthis case, the light detection unit may be disposed between the resetterminal of any one sub-pixel unit and the data line.

In other embodiments of the present disclosure, for each OLED pixel unit221, the light detection units 222, the number of which is not more thanthe number of the sub-pixel units of the OLED pixel unit 221, may alsobe provided. In this case, one light detection unit 222 may be connectedbetween the reset terminal of a portion of the sub-pixel units or eachsub-pixel unit and the data line, respectively. FIG. 2 shows a casewhere one light detection unit 222 is connected between the resetterminal of each sub-pixel unit 222 and the data line.

In the embodiments of the present disclosure, the number of the lightdetection units is not specifically limited. A person skilled in the artcan select the number of the light detection units according to asensitivity of fingerprint recognition actually required. As shown inFIG. 1, in the case where a finger touches the OLED display panel 10, aridge 31 of the fingerprint is in contact with the transparent substrate1, and a valley 32 of the fingerprint is not in contact with thetransparent substrate 1. The light detection unit corresponding to theridge 31 of the fingerprint detects an intensity of a light reflected bythe composite interface composed of the ridge 31 of the fingerprint andthe transparent substrate 1. And the light detection unit correspondingto the valley 32 of the fingerprint detects the intensity of a lightreflected by the transparent substrate 1 only. The light detection unit222 converts the detected light intensity into an electrical signal.Under a control of a reset signal from the reset terminal, theelectrical signal is output to the fingerprint recognition unit (notshown) through the data line. Thus, the fingerprint recognition unit canrecognize the ridges and valleys of the fingerprint based on thereceived electrical signal so as to draw a fingerprint pattern, therebyperforming fingerprint recognition.

In an exemplary embodiment, a orthographic projection of the lightdetection unit 222 on the substrate 21 does not overlap with aorthographic projection of the organic light emitting layer of the OLEDpixel unit 221 on the substrate 21. As an example, the light detectionunit is arranged in a staggered manner with the organic light emittinglayer, thus the light reflected by the transparent substrate or thecomposite interface composed of the transparent substrate and the ridgesof the fingerprint can enter into the light detection unit without beingblocked. The staggered arrangement described above can recognize theridges and valleys of the fingerprint more accurately, thereby improvingthe accuracy of fingerprint recognition.

FIG. 2 is a schematic plan view of one example of an OLED display panelaccording to an embodiment of the present disclosure. For clarity, thetransparent substrate is not shown in FIG. 2. As shown in FIG. 2, theOLED array substrate 2 comprises a plurality of data lines, a pluralityof scan lines, a plurality of OLED pixel units 400, a plurality of lightdetection units 200, and a fingerprint recognition unit 300. The OLEDpixel unit 400 comprises three sub-pixel units 100. FIG. 2 shows a casewhere each OLED pixel unit 400 is connected with three light detectionunits 200. That is, one light detection unit 200 is connected betweenthe reset terminal Reset of each sub-pixel unit 100 and the data line.It can be understood that each OLED pixel unit 400 may be connected withone or two or three light detection units 200 according to therequirements of the sensitivity of fingerprint recognition, which willnot be described herein.

It should be noted that the one OLED pixel unit shown in FIG. 2comprising three stripe-arranged sub-pixel units is merely exemplary. Inthe embodiments of the present disclosure, the arrangement of aplurality of sub-pixel units is not specifically limited. A personskilled in the art can arrange a plurality of sub-pixel units accordingto actual needs.

As an example, as shown in FIG. 2, the sub-pixel unit 100 is connectedto the data line D(N), the scan line G(N), and the reset terminal Reset.The reset terminal Reset can receive a signal from the scan line G (N−x)as a reset signal, wherein the value of x is not less than 1. Forexample, the reset terminal Reset may receive a signal from the scanline G(N−1). The light detection unit 200 is connected between the resetterminal Reset of the sub-pixel unit 100 and the data line D(N). Thefingerprint recognition unit 300 is connected to the data lines D(N−1),D(N), D(N+1) . . . .

In an exemplary embodiment, the plurality of scan lines can input scansignals when the OLED display panel is displaying, so as to open aplurality of OLED pixels included in a row corresponding to the scanlines. The plurality of data lines can input data signals correspondingto the video signals when the OLED display panel is displaying, so as toenable the plurality of OLED pixels included in a column correspondingto the data lines to emit light. Each OLED pixel unit 400 is connectedto a corresponding data line and a corresponding scan line. That is,each sub-pixel unit 100 is connected to the corresponding data line andthe corresponding scan line and can display according to the respectivescan signal and data signal.

The light detection unit 200 can detect the properties of light, forexample, the intensity of light, and generate a respective lightdetection signal. FIG. 3 is a schematic structural diagram of a lightdetection unit 200 according to an embodiment of the present disclosure.As shown in FIG. 3, the light detection unit 200 comprises a firsttransistor TP and a photodetector PD. A first electrode of the firsttransistor TP is coupled to the data line D(N). A second electrode ofthe first transistor TP is coupled to the photodetector PD. A controlelectrode of the first transistor TP is coupled to the reset terminalReset. Each light detection unit 200 is connected between the resetterminal Reset of one sub-pixel unit 100 and the data line, and candetect a light reflected by the transparent substrate 1 to generate alight detection signal. In addition, the light detection unit 200 canoutput the light detection signal via the data line under a control ofthe reset signal from the reset terminal Reset. That is, thephotodetector PD can detect the intensity of the light reflected by thetransparent substrate 1 or the composite interface composed of thetransparent substrate 1 and the ridges of the fingerprint. Then, thephotodetector PD can convert the intensity of the detected light into anelectrical signal (light detection signal). For example, the electricalsignal is current. Since the reset signal from the reset terminal Resetcan turn on the first transistor TP, the current is transmitted to thefingerprint recognition unit 300 via the data line and through the firsttransistor TP.

As an example, the first electrode of the first transistor TP is adrain, and the second electrode is a source. As another example, thefirst electrode of the first transistor TP is a source, and the secondelectrode is a drain. In an exemplary embodiment, the photodetector PDcomprises a photodiode.

The fingerprint recognition unit 300 is connected to the plurality ofdata lines, and can recognize a fingerprint pattern based on lightdetection signals from the plurality of data lines. That is, thefingerprint recognition unit 300 receives the current transmitted viathe data line, recognizes the ridges and valleys of the fingerprintbased on the current, and draws a fingerprint pattern. Therefore, thedrawn fingerprint pattern can be compared with the stored fingerprintpattern to perform fingerprint recognition.

In the embodiments of the present disclosure, the structure of thesub-pixel unit 100 is not specifically limited as long as the sub-pixelunit 100 can emit light. As an example, a transistor (not shown) in thesub-pixel unit 100 and the first transistor TP in the light detectionunit 200 are P-type transistors. As another example, the transistor inthe sub-pixel unit 100 and the first transistor TP in the lightdetection unit 200 are N-type transistors. It should be noted that thedescription herein is directed to the case where the transistor in thesub-pixel unit 100 and the first transistor TP in the light detectionunit 200 are P-type transistors. A person skilled in the art canunderstand that, for the case where the transistor is an N-typetransistor, the same function can be realized by changing the voltage ofthe control electrode of the transistor to the opposite polarity, whichwill not be described herein.

FIG. 4 is an exemplary pixel circuit schematic diagram of an OLEDdisplay panel according to an embodiment of the present disclosure. Thepixel circuit for the OLED display panel comprises a light emittingdrive circuit being configured to control an OLED pixel unit to emitlight, and a light detection unit being configured to detect a lightemitted by a detection light resource to generate a light detectionsignal.

The transistor in FIG. 4 is a P-type transistor. It can be understoodthat the transistor in FIG. 4 may be an N-type transistor. As shown inFIG. 4, the light detection unit 200 comprises a first transistor TP anda photodetector PD. A first electrode of the first transistor TP iscoupled to the data line D(N). A second electrode of the firsttransistor TP is coupled to the photodetector PD. A control electrode ofthe first transistor TP is coupled to the reset terminal Reset. In FIG.4, an initialization transistor T1, a second transistor T2, a thirdtransistor T3, a fourth transistor T4, a fifth transistor T5, a sixthtransistor T6, a driving transistor DTFT, a capacitor Cst, and an OLEDlight emitting device constitute a light emitting drive circuit of apixel unit. Among them, the driving transistor DTFT is used to drive theOLED light emitting device to emit light.

As shown in FIG. 4, a control electrode of the initialization transistorT1 is coupled to the reset terminal Reset, a first electrode of theinitialization transistor T1 is coupled to a first terminal of thecapacitor Cst, and a second electrode of the initialization transistorT1 is used for receiving an initial supply voltage Vint. A controlelectrode of the second transistor T2 is coupled to a corresponding scanline, a first electrode of the second transistor T2 is coupled to asecond electrode of the driving transistor DTFT, and a second electrodeof the second transistor T2 is coupled to the first terminal of thecapacitor Cst. A control electrode of the third transistor T3 is coupledto the corresponding scan line, a first electrode of the thirdtransistor T3 is coupled to the corresponding data line, and a secondelectrode of the third transistor T3 is coupled to a first electrode ofthe driving transistor DTFT. A control electrode of the fourthtransistor T4 is coupled to a light emission control signal line, afirst electrode of the fourth transistor T4 is coupled to the firstelectrode of the driving transistor DTFT, and a second electrode of thefourth transistor T4 is coupled to a second terminal of the capacitorCst. A control electrode of the fifth transistor T5 is coupled to thelight emission control signal line, a first electrode of the fifthtransistor T5 is coupled to the OLED light emitting device, and a secondelectrode of the fifth transistor T5 is coupled to the second electrodeof the driving transistor DTFT. A control electrode of the sixthtransistor T6 is coupled to the reset terminal Reset, a first electrodeof the sixth transistor T6 is used for receiving the initial supplyvoltage Vint, and a second electrode of the sixth transistor T6 iscoupled to the OLED light emitting device. A control electrode of thedriving transistor DTFT is coupled to the first terminal of thecapacitor Cst, the first electrode of the driving transistor DTFT iscoupled to the first electrode of the fourth transistor T4, and thesecond electrode of the driving transistor DTFT is coupled to the secondelectrode of the fifth transistor T5.

In the embodiments of the present disclosure, there is provided adriving method of the above-described pixel circuit. The pixel circuitcomprises during a first time period t1, resetting an OLED pixel unit,during a second time period t2, storing a data voltage for displaying,and during a third time period t3, driving the OLED pixel unit to emitlight.

FIG. 5 is an operation timing chart of a pixel circuit of an OLEDdisplay panel according to an embodiment of the present disclosure. InFIG. 5, a first time period t1 corresponds to a reset time period of theOLED pixel unit 400 of the OLED display panel 10; a second time periodt2 corresponds to a storing time period for storing the data voltage fordisplaying; a third time period t3 corresponds to a light emitting timeperiod of the OLED pixel unit 400 of the OLED display panel 10. For theexample that the OLED pixel unit 400 comprises three sub-pixel units100, the first time period t1 corresponds to the reset time period ofrespective sub-pixel unit 100, the second time period t2 corresponds tothe data voltage storing time period of respective sub-pixel unit 100,and the third time period t3 corresponds to the light emitting timeperiod of respective sub-pixel unit 100. During the first time periodt1, a light detection signal is output through the data line. During thesecond time period t2, a data signal for display is input through thedata line. The operation of the circuit in FIG. 4 will be describedbelow with reference to the operation timing chart in FIG. 5.

As shown in FIG. 5, during the first time period t1, a low level signalis input into the reset terminal Reset. The initialization transistor T1is turned on. An initial supply voltage Vint provides an initializationvoltage to a A terminal of the capacitor Cst, so as to initialize the Aterminal of the capacitor Cst and the control electrode of the drivingtransistor D-TFT, thereby resetting the OLED pixel units in Nth row. Atthis time, the OLED pixel units in Nth row do not emit light, while atleast the OLED pixel units in (N+x)th rows emit monochromatic light. Itshould be noted that, specifically, which row (i.e. the value of x)emits the monochromatic light is determined by the timing of resetting,charging and emitting of the unit pixel corresponding to the resolutionof the OLED display panel. At the same time, the sixth transistor T6 isalso turned on. The initial supply voltage Vint provides a reverse biasvoltage to the OLED light emitting device through the sixth transistorT6. In addition, the first transistor TP is also turned on. At thistime, the photodetector PD can detect the intensity of the monochromaticlight from the OLED pixel unit in (N+x)th row reflected by thetransparent substrate 1 or the composite interface composed of thetransparent substrate 1 and the ridges of the fingerprint, and convertthe intensity into an electrical signal. In addition, since the firsttransistor TP is turned on, the electrical signal is output to thefingerprint recognition unit (not shown) via the data line D(N).

During the second time period t2, a low level signal is input into thescan line G(N). The second transistor T2 is turned on. At this time, thesecond transistor T2 is coupled between the control electrode of thedriving transistor D-TFT and the first electrode to form a diodeconnection to compensate a threshold voltage of the driving transistorD-TFT. In addition, the third transistor T3 is also turned on. A datasignal is input into the data line D(N), and the A terminal of thecapacitor Cst can be charged via the third transistor T3 and the drivingtransistor D-TFT to store the data voltage representing the data signalin the capacitor Cst.

During the third time period t3, a low level signal is input into alight emission control signal line EM(N). The fourth transistor T4 isturned on. A first supply voltage ELVDD supplies a supply voltage to thedrive transistor D-TFT. In addition, the fifth transistor T5 is alsoturned on. The OLED light emitting device may emit light by providing adriving voltage to the OLED light emitting device through the drivingtransistor D-TFT. In this time period, the data voltage stored in thecapacitor Cst and the threshold voltage of the driving transistor D-TFTmay be applied through the driving transistor D-TFT to enable the OLEDlight emitting device to emit light.

In addition, FIG. 4 is merely an exemplary circuit diagram. The circuitdiagram included in the embodiments of the present disclosure maycomprise various forms as long as the light detection unit 200 isconnected between the reset terminal Reset of the corresponding OLEDpixel unit and the data line D(N).

In an embodiment of the present disclosure, a method for fingerprintrecognition using an OLED display panel is also provided. FIG. 6 is aflowchart of a method for fingerprint recognition using an OLED displaypanel according to an embodiment of the present disclosure. The OLEDdisplay panel may be, for example, the OLED display panel as shown inFIG. 1 or FIG. 2. As shown in FIG. 6, the method comprises step S601 tostep S604.

In step S601, it is detected that a user's finger touching the OLEDdisplay panel. As an example, when fingerprint recognition is required,the OLED display panel may display a region which indicates the user toperform fingerprint recognition. Then, the user can touch thefingerprint recognition region with a finger. In an embodiment of thepresent disclosure, it may be detected whether the user's finger touchesthe fingerprint recognition region for a predetermined time. Afterdetecting that the user's finger has touched and stayed in thefingerprint recognition region for a predetermined time, step S602 isperformed.

In step S602, the OLED pixel unit of the OLED display panel iscontrolled to emit light for fingerprint recognition. In the embodimentsof the present disclosure, the light for fingerprint recognition may bemonochromatic light. As an example, the OLED pixel unit may emitmonochromatic light of short timing for fingerprint recognition. Theshort-timing monochromatic light does not affect human eyes from viewingthe original screen displayed by the OLED display panel. For example,the short timing does not exceed 30 ms. In the embodiments of thepresent disclosure, the color of the monochromatic light is notspecifically limited as long as the monochromatic light emitted by theOLED pixel unit is the light having the same property. For example, themonochromatic light may be a single color of light formed by red light,green light, blue light, or a combination thereof.

In step S603, a light detection signal is obtained in a reset stage ofthe OLED pixel unit of the OLED display panel. In the embodiments of thepresent disclosure, after the user's finger touching the transparentsubstrate of the OLED display panel, the OLED pixel unit emitsmonochromatic light, and the photodetector in the OLED display panel maydetect the intensity of a light reflected by the transparent substrateor the composite interface composed of the transparent substrate and theridges of the fingerprint, and convert the light intensity into anelectrical signal (e.g. current) as a light detection signal. Then, in areset stage of the OLED pixel unit of the OLED display panel, the lightdetection signal is output to the fingerprint recognition unit via thedata line.

In step S604, a fingerprint pattern of the user's finger is recognizedbased on the light detection signal. As an example, after receiving theelectrical signal as the light detection signal, the fingerprintrecognition unit processes the electrical signal to determine whetherthe respective OLED pixel unit covered by the finger corresponds to theridge or the valley of the fingerprint. Then, a fingerprint pattern isdrawn, and the characteristics of the resulting fingerprint pattern arecompared with the characteristics of the stored fingerprint pattern,thus performing fingerprint recognition.

In an exemplary embodiment, the entire display region of the OLEDdisplay panel may be used as the fingerprint recognition region.

In an exemplary embodiment, a region for fingerprint recognition may bespecified in a display region of the OLED display panel. For example,the display region at the bottom of the OLED display panel may bedesignated as the fingerprint recognition region.

The application of fingerprint recognition using the above-describedOLED display panel is described below. As an example, when using adisplay terminal comprising the OLED display panel described above forelectronic payment, first, the display terminal recognizes that the userneeds to perform fingerprint recognition, and displays a fingerprintrecognition region on the OLED display panel to instruct the user toperform fingerprint recognition. The fingerprint recognition region maybe the entire display region of the OLED display panel, or may be aspecific display region of the OLED display panel (for example, adisplay region at the bottom of the OLED display panel). When the usertouching the fingerprint recognition region, the display terminaldetects that the user's finger is placed and has stayed in thefingerprint recognition region. Then, the OLED display panel emitsmonochromatic light for fingerprint recognition, and the monochromaticlight does not affect the normal display of the OLED display terminal.The OLED display panel obtains the user's fingerprint pattern andcompares this fingerprint pattern with the stored fingerprint patternfor electronic payment.

In the embodiments of the present disclosure, the light detection unitis integrated in the OLED display panel. The light emitted by the OLEDdisplay panel can be used for display as well as a light source forfingerprint recognition. The OLED display panel can perform fingerprintrecognition while displaying without affecting the accuracy offingerprint recognition. In addition, each sub-pixel unit of the OLEDdisplay panel may correspond to one light detection unit, which canimprove the accuracy and sensitivity of fingerprint recognition.

In the embodiments of the present disclosure, an electronic device 70comprising the above-described OLED display panel 10 is also provided.As shown in FIG. 7, the electronic device 70 may be, for example, amobile phone, a tablet, a television, a display, a laptop, a navigator,a wearable device, an e-book reader, or the like.

The foregoing description of the embodiment has been provided forpurpose of illustration and description. It is not intended to beexhaustive or to limit the application. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the application, and all such modificationsare included within the scope of the application.

The invention claimed is:
 1. A pixel circuit for an OLED display panel,wherein the OLED display panel comprising an OLED array substratecomprises: a transparent substrate disposed opposite to the OLED arraysubstrate, wherein the OLED array substrate comprises: a plurality ofscan lines; a plurality of data lines being configured to input datasignals corresponding to the video signals; a plurality of OLED pixelunits, each of the OLED pixel units being connected to a correspondingdata line and a corresponding scan line and being connected to acorresponding reset terminal; and a plurality of light detection units,each of the light detection units being connected between the resetterminal of one of the OLED pixel units and the corresponding data line,and being configured to detect a light emitted by a detection lightresource to generate a light detection signal and output the lightdetection signal via the corresponding data line under a control of areset signal from the reset terminal, and a fingerprint recognition unitwhich is connected to the plurality of data lines and is configured torecognize a fingerprint pattern based on the light detection signalsfrom the plurality of data lines, the pixel circuit comprises: a lightemitting drive circuit being configured to control an OLED pixel unit toemit light; and a light detection unit being configured to detect alight emitted by a detection light resource to generate a lightdetection signal, wherein the light detection unit comprises a firsttransistor and a photodetector, a first electrode of the firsttransistor is coupled to a corresponding data line, a second electrodeof the first transistor is coupled to the photodetector, and a controlelectrode of the first transistor is coupled to a reset terminal whereinthe light emitting drive circuit comprises a capacitor, aninitialization transistor, a second transistor, a third transistor, afourth transistor, a fifth transistor, a sixth transistor, a drivingtransistor, and an OLED light emitting device, wherein a controlelectrode of the initialization transistor is coupled to the resetterminal, a first electrode of the initialization transistor is coupledto a first terminal of the capacitor, and a second electrode of theinitialization transistor is used for receiving an initial supplyvoltage, a control electrode of the second transistor is coupled to acorresponding scan line, a first electrode of the second transistor iscoupled to a second electrode of the driving transistor, and a secondelectrode of the second transistor is coupled to the first terminal ofthe capacitor, a control electrode of the third transistor is coupled tothe corresponding scan line, a first electrode of the third transistoris coupled to the corresponding data line, and a second electrode of thethird transistor is coupled to a first electrode of the drivingtransistor, a control electrode of the fourth transistor is coupled to alight emission control signal line, a first electrode of the fourthtransistor is coupled to the first electrode of the driving transistor,and a second electrode of the fourth transistor is coupled to a secondterminal of the capacitor, a control electrode of the fifth transistoris coupled to the light emission control signal line, a first electrodeof the fifth transistor is coupled to the OLED light emitting device,and a second electrode of the fifth transistor is coupled to the secondelectrode of the driving transistor, a control electrode of the sixthtransistor is coupled to the reset terminal, a first electrode of thesixth transistor is used for receiving the initial supply voltage, and asecond electrode of the sixth transistor is coupled to the OLED lightemitting device, and a control electrode of the driving transistor iscoupled to the first terminal of the capacitor, the first electrode ofthe driving transistor is coupled to the first electrode of the fourthtransistor, and the second electrode of the driving transistor iscoupled to the second electrode of the fifth transistor.
 2. A drivingmethod of the pixel circuit according to claim 1, comprising: during afirst time period, resetting an OLED pixel unit, during a second timeperiod, storing a data voltage for displaying, and during a third timeperiod, driving the OLED pixel unit to emit light.
 3. A method forfingerprint recognition using the OLED display panel according to claim1, comprising: detecting a user's finger touching the OLED displaypanel; controlling an OLED pixel unit of the OLED display panel to emita light for fingerprint recognition; obtaining a light detection signalin a reset stage of the OLED pixel unit of the OLED display panel,wherein the light detection signal is generated by detecting the lightfor fingerprint recognition reflected by the transparent substrate ofthe OLED display panel; and recognizing a fingerprint pattern of theuser's finger based on the light detection signal.
 4. The methodaccording to claim 3, further comprising: setting a region forfingerprint recognition in a display region of the OLED display panel,wherein the detecting that a user's finger touching the OLED displaypanel comprises: detecting that a user's finger touching the region forfingerprint recognition for a predetermined time.
 5. The methodaccording to claim 3, wherein the light for fingerprint recognition ismonochromatic light.
 6. An electronic device comprising the OLED displaypanel according to claim
 1. 7. The pixel circuit according to claim 1,wherein the light emitted by the detection light resource is a lightreflected by the transparent substrate.
 8. The pixel circuit accordingto claim 1, wherein the light emitted by the detection light resource ismonochromatic light.
 9. The pixel circuit according to claim 1, whereinthe detection light resource is the OLED pixel unit.
 10. The pixelcircuit according to claim 1, wherein the photodetector comprises aphotodiode.
 11. The pixel circuit according to claim 1, wherein aorthographic projection of the light detection unit on a substrate ofthe OLED array substrate does not overlap with a orthographic projectionof an organic light emitting layer of the OLED pixel unit on thesubstrate.
 12. The pixel circuit according to claim 1, wherein the OLEDpixel unit comprises a plurality of sub-pixel units, one of the lightdetection units is connected between the reset terminal of at least oneof the sub-pixel units and the corresponding data line.